Human Anatomy, First Edition McKinley

1
Human Anatomy, First EditionMcKinley O'Loughlin

• Chapter 2 Lecture Outline
• The Cell Basic Unit of Structure and Function

2
The Cell

• Cells are the structural and functional units of
  all living organisms.
• They are the building blocks of the human body.
• An adult human body contains about 75 trillion
  cells.
• Each cell type in the body performs specific
  functions.

3
Common Characteristics of Cells

• All cells perform the general functions necessary
  to sustain life.
• Obtain nutrients and other materials essential
  for survival from its surrounding fluids.
• Dispose of the wastes they produce
• Shape and integrity
• Cell division

4
(No Transcript)
5
Cells

• Most cells in the human body are between 1
  micrometer (mm) and 100 mm in diameter.
• Individual cells are usually observed by light
  microscopy
• Subcellular structures are studied by electron
  microscopy.

6
Plasma (Cell) Membrane

• The plasma membrane forms the outer, limiting
  barrier separating the internal contents of the
  cell from external materials.

7
(No Transcript)
8
Cytoplasm

• Cytoplasm is a general term for all cellular
  contents located between the plasma membrane and
  the nucleus.

9
Nucleus

• The nucleus is the cells control center.
• It controls protein synthesis and directs the
  functional and structural characteristics of the
  cell.

10
Facilitated Diffusion

• Requires the participation of specific transport
  proteins that help specific substances or
  molecules move across the plasma membrane.

11
Bulk Filtration

• Involves the diffusion of both solvents and
  solutes together across the selectively permeable
  membrane.

12
Active Transport

• Movement of a substance across a plasma membrane
  against a concentration gradient.
• Materials must be moved from an area of low
  concentration to an area of high concentration.
• requires cellular energy in the form of ATP
  (adenosine triphosphate) and sometimes a
  transport protein as well
• ATP is continually synthesized by mitochondria

13
Ion Pumps

• Active transport processes that move ions across
  the membrane are called ion pumps.
• ion pumps allow a cell to maintain its internal
  concentrations of small molecules or ions

14
Bulk Transport - Exocytosis

• The means by which large molecules are secreted
  from the cell is called exocytosis.

15
(No Transcript)
16
Bulk Transport - Endocytosis

• Endocytosis is a process whereby the cell
  acquires materials from the extracellular fluid.
  (3 Forms)
• phagocytosis occurs when membrane extensions,
  termed pseudopodia, engulf a particle and
  internalize it into a vacuole
• pinocytosis is the incorporation of droplets of
  extracellular fluid into the cell in small
  vesicles
• receptor-mediated endocytosis is when receptors
  with specific molecules bound to them aggregate
  within the membrane, and then an invagination
  forms around them to create a cytoplasmic vesicle
  

17
(No Transcript)
18
(No Transcript)
19
Passive Transport

• Movement of substances along a concentration
  gradient
• ATP is not required

20
Organelles

• Organelles are complex, organized structures with
  unique, characteristic shapes.
• Each type of organelle performs a different
  function for the cell.
• Collectively, the specialized functions of all
  organelles are essential for normal cellular
  structure and activities.

21
(No Transcript)
22
(No Transcript)
23
(No Transcript)
24
(No Transcript)
25
(No Transcript)
26
(No Transcript)
27
Mitochondria

• Mitochondria are organelles with a double
  membrane.
• Produce large amounts of ATP.
• Are called the powerhouses of the cell.

28
(No Transcript)
29
Ribosomes

• Ribosomes are very small, dense granules that are
  responsible for protein production (synthesis).
• Each ribosome has a small and a large subunit.
• The small subunit is about one-half the size of
  the large subunit.

30
(No Transcript)
31
The Cytoskeleton

• Filamentous proteins form the cytoskeleton, which
  helps give the cell its shape and coordinates
  cellular movements.
• microfilaments
• intermediate filaments
• microtubules

32
(No Transcript)
33
(No Transcript)
34
Membranous Organelles

• Some organelles are surrounded by a membrane.
• They are called membrane-bound organelles, or
  membranous organelles.

35
Cilia and Flagella

• Appendages extending from the surface of some
  cells.
• Cilia usually occur in large numbers they work
  together to move materials or fluids along the
  surface of a cell.
• Flagella are longer than cilia, and usually occur
  as single appendages.

36
(No Transcript)
37
The Nucleus

• The nucleus is the central core, or the control
  center, of cellular activities.
• Usually, it is the largest structure within the
  cell and appears as a single spherical or oval
  structure.

38
(No Transcript)
39
The Nucleus

• The nucleus is enclosed by a double membrane
  structure called the nuclear envelope.
• The nuclear envelope controls the entry and exit
  of materials between the nucleus and the
  cytoplasm.

40
Nucleolus

• The cell nucleus may contain one or more usually
  spherical, darkstaining bodies called nucleoli.
• Nucleoli are responsible for making the small and
  the large subunits or ribosomes.

41
Chromatin and DNA

• DNA is the genetic material housed within the
  nucleus of the cell.
• DNA is a polymer of nucleotides (sugar,
  phosphate, nitrogen base) in the shape of a
  double helix.
• Strands of DNA and histone proteins associate
  within the nucleus to form chromatin.

42
Insert Figure 2.18
43
Chromosome

• The chromosome is the most organized level of
  genetic material.
• Each chromosome contains a single, long molecule
  of DNA and associated proteins.
• Chromosomes become visible only when the cell is
  dividing.

44
The Cell Cycle

• The life cycle of the cell is called the cell
  cycle.
• New cells must be made continuously in order for
  an organism to grow and replace its damaged
  cells.

45
(No Transcript)
46
Mitosis and Meiosis

• There are two types of cell division.
• Mitosis is the cell division process that takes
  place in somatic cells.
• Sex cells undergo a cell division process called
  meiosis.

47
Mitosis

• Interphase
• Prophase
• Metaphase
• Anaphase
• Telophase
• Cytokinesis

48
Tumor

• Normal tissue development exhibits a balance
  between cell division and cell death.
• If this balance is upset and cells multiply
  faster than they die, abnormal growth results in
  a new cell mass that is called a neoplasm, or
  tumor.

49
Cancer

• Benign neoplasms usually grow slowly and are
  confined within a connective tissue capsule.
• Cells within these tumors dedifferentiatethat
  is, they revert to a less specialized state, and
  cause an increase in their own vascular supply to
  support their growth.
• These tumors are usually not lethal, but they
  have the potential to become life-threatening if
  they compress brain tissue, nerves, blood
  vessels, or airways.

50
Cancer

• Cancer is the general term used to describe a
  group of diseases characterized by various types
  of malignant neoplasms.
• unencapsulated
• contain cells that dedifferentiate
• increase their vascular supply
• grow rapidly
• spread easily to other organs by way of the blood
  or lymph (metastasis)

51
Cancer

• Cancer cells lose control of their cell cycle.
• they divide too frequently and grow out of
  control
• cancer cells lose contact inhibition
• they overgrow one another and lack the ability to
  stop growing and dividing when they crowd other
  cells

52
Cancer Cells

• Exhibit dedifferentiation and revert to an
  earlier, less specialized developmental state.
• Produce chemicals that cause local blood vessel
  formation resulting in increased blood vessels in
  the developing tumor (angiogenesis).
• Have the ability to squeeze into any space
  (invasiveness) permitting them to leave their
  place of origin and travel elsewhere in the body.
  
• Acquire the ability to metastasizethat is,
  spread to other organs in the body.